Originally Posted by Lady's Human
The reason that the National Guard is the force in question rather than the regular army is Posse Comitatus. This law prevents federal military forces from being used in a law enforcement role within the borders of the United States.
If anyone had any true intestinal fortitude (and this includes everyone on Capitol Hill, not just republicans or just democrats) they would revise Posse Comitatus and allow Federal Forces to be used on the border areas to protect the border. The excesses from the post-Civil War era are long since over, and like many other statutes that have gathered dust over the years need to be revised.